l02 steel design kaea3218
TRANSCRIPT
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Dr. Meldi SuhatrilDepartment of Civil Engineering,
Faculty of Engineering, University of Malaya.
STRUCTURAL STEEL DESIGN (KAEA 3218)
- Steel properties-
Better quality control
Lighter
Faster to erect
Reduced site time Fast track construction Large column free space and amenable for
alteration
Less material handling at site
Less percentage of floor area occupied by
structural elements
Has better duct ili ty and hence superior
lateral load behavior; better earthquake
resistance
Advant ages of Steel Design
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
Skilled labor is required
Higher cost of construction Maintenance cost is high
Poor fireproofing, as at 1000 F (538 C) &
at 1600 F (871 C) 15% strength remains
Electricity may be required
Disadvantage of Steel Design
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
Steel is an alloy of Iron, Carbon (
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Yield Strength (fy) = 220 540 Mpa
Ultimate Tensile Strength = 1.2 fy Modulus Elasticity(E) = 2 x 106 N/mm2
Shear Modulus (G) = 0.4E
Poisson Ratio ()
- Elastic Range = 0.3
- Plastic Range= 0.5
coefficient of linear thermal expansion
Mechanical Propert ies of St ructural Steel
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
St ress Strain Curve for Structural Steel
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
Yield Strength & Ult imat e Tensile Strength
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
Steel sect ion
1. Hot rolled Sections - heated up and pushed through
rollers that squeeze the metal into a particular profile,
depending on the shape of the rollers.
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
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Steel sect ion
2. Cold formed section - are created by the working of
sheet steel using stamping, rolling, or presses todeform the sheet into a profile
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
Steel sect ion
3. Built-up form a shape by welding together
different hot-rolled sections
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
Sect ion Propert ies
Labellingb
h d
tw
tf
r
y y
z
z
t
b
r
h y y
z
z
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
Sect ion Propert ies
Typical section properties for design
resistance calculation
A Area
Wel Elastic modulus
Wpl Plastic modulus
IySecond moment of area major
axis
IzSecond moment of area minor
axis
i Radius of gyration
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
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St ructural Design
Principle design requirements:
a) Structural requirements:
Safety produce a structure which will not fail in itsdesign lifetime, or has an acceptably low risk of failure
Stiffness of the structure sufficient to ensure that theserviceability of the structure is not impaired byexcessive deflections, vibrations and the like.
b) Other requirements:
Economy the type and quantity of materials, methodsof fabricating and constructions, sizes of the membersof the structure.
Harmony relationships between the different systemsof the structure i.e. the structural system (loadresistance and transfer system), the architecturalsystem, the electrical and mechanical system andenvironment.
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
Overall Design
Process1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
St ructural Design Process
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
St ructural Design Process
Design procedure for structural framework design:
a) Planning establish the functions of the structure
b) Preliminary structural configuration arrangement of the elements
c) Establishment of the loadsd) Preliminary member selection
e) Analysis
f) Evaluation all of the above requirements aresatisfied and compare with predetermined criteria
g) Redesign repetition of the sequences areneeded based on the evaluation
h) Final decision whether optimum design hasbeen achieved
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
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Limit State Design
Safety is a paramount responsibility of the
designer In the design, there are uncertainty due to
many factors, which affect the safety:
Loading
Material strength
Structural dimension and behaviour
Designer must ensure that the risk of failure
is extremely small, despite the
uncertainties.
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
Limit State Design
Basis of LS design the probability ofoperating conditions not reaching failureconditions
Limit States are the various conditions inwhich a structure would be considered tohave failed to fulfill the purpose for which itwas built.
Two limit states are considered at thedesign stage:
Ulti mat e limit stat e (ULS)
Serviceabilit y lim it stat e (SLS)
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design
Limit State Design
ULS catastrophic states, when ULS are reached whole structure or part of it collapses
Strength (yield, buckling)
Stability against overturning and sway
Fracture due to fatigue
Brittle fracture
SLS limits on acceptable performance of thestructure, when SLS are reached structure unfit for
normal use but do not indicate collapse
Deflection
Vibration
Fatigue checks
corrosion
1.Advantages & Disadvantages
2.Properties
- Material
- Mechanical
3.Steel Section
- Hot Rolled
- Cold form
- Built-up
4. Section Properties
5.Structural Design
6.Limit State Design